Taxicab call system



Filed oct: 18, 1940 2 sheets-sheet 2 V @95cm mb .w p WILLI. Ens@ Rm m NQ QF Ef QS, .Y c mw m mm Nm, SENS@ Reb Y bm. QQQM. haw

Patented Mar. 24, 1942 2,277,649 TAXICAB CALL SYSTEM Bernard D. Willis,

Associated Electric Oak Park, Ill., assigner to Laboratories, Inc., Chicago,

Ill., a corporation of Delaware v Application October 1S, 1940, Serial No. 361,675

21 Claims. l (Cl. 179-2) The present invention relates to signaling systems, and more particularly to improvements in signaling systems designed for use in regulating the movement of public service vehicles such as taxicabs.

As explained in Patent No. 2,023,225, granted December 3, 1935, Bernard D. Willis and Harvey L. Harris, a factor contributing largely to confusion of traliic in metropolitan areas resides in the almost continuous cruising or idle movement of public taxicabs, the drivers of which are scouting for passengers or fares. In this patent there is disclosed a system for governing the movement of cabs in such a manner that the cabs are under complete control of a centrally located supervisory point or cab stand from which the cabs may be dispatched to various calling stations in response to cab call signals transmitted to the supervisory point. In the disclosed arrangement, the call stations are connected to signaling circuits or lines extending to the control or master station located at the supervisory point, and call buttons are provided for transmitting the call signals over the lines to the control station. An electromagnetically controlled mechanical lockout arrangement is utilized for limiting the system to the handling of one call at a time.

It is an object oi the present invention to provide an improved system of the character described, Which is so arranged that the call signals are transmitted to the cab stands from which cabs may be dispatched to the calling points with a minimum of traiiic confusion.

It is another object of the invention to provide an improved cab call system of the character described, Which is so arranged that the cab call signals are transmitted to cab stands from Which cabs may proceed to the calling points over routes requiringa minimum number of traflic turns of the same type.

It is a further object of the invention to provide, in a system of the character described, an improved and exceedingly simple lockout arrangement, entirely electrical in character, for preventing any signaling line from being occupied with more than one call at any given time.

It is still another object of the Ainvention to provide, in a system of the character described, an improved arrangement for signaling a calling party as to the idle or busy condition of a line upon which a call is initiated, and for enabling the calling party to determine when the line becomes idle.

It is a still further object of the invention to provide' a signaling system of the character described, which is simple to operate, requires a minimum amount of equipment, and is positive and reliable in the performance of its intended functions.

The invention is illustrated in its embodiment in the business district of a metropolitan area which includes both one and two-Watr streets arranged to form the conventional grid type of street pattern. The call signals are disposed along opposite sides of each street, and the cab stands, of which there are two, are located at oppositely disposed corners of the congested trafiic area so that they are disposed on opposite sides of the two-Way streets at points therealong where the traiiic congestion starts. Each cab stand is equipped with a control or dispatcher station from which the signaling circuits or lines are fanned out to the various call stations. In

accordance with the present invention, the call stations located along one side of each two-Way street are served by signaling circuits Which extend to the control station at one of the cab stands, While the call stations located along the opposite side of each two-Way street are connected to signaling circuits which extend to the control stations provided at the other of the cab stands. By virtue of this arrangement, cabs dispatched to various calling points are required to make the least confusing type of traic turn, namely, right-hand turns. In further develop- `ment of this concept, the call stations disposed along opposite sides of each one-Way street are connected to signaling circuits which extend to the control station at the same cab stand, the particular control station being determined by the assigned direction of traine flow over the particular street, whereby cabs summoned to the call station disposed along the one-Way streets are requiredv to make only right-hand turns in entering such streets.

In the physical embodiment of the system, each signaling circuit or line extends from the master station to a plurality lof call stations. The master station is equipped With a signal control relay for indicating the presence of a call on each line, and each of the call stations is provided with a call relay and a switch for connecting the associated call relay in series with the signal control relay connected with the line at the master station. The release of any operated call relay is under the control of means provided at the master station for establishing a low resistance shunt across the operated call relay to cause the deenergization thereof. Provisions are also made whereby not more than one of the call relays can be operated at any one time. In one embodiment of the physical arrangement, each call station is equipped with a transmitter and receiver, whereby exact information may be dispatched to the control station as to the location of a calling party. In order to permit a calling party to determine when a busy line becomes idle, an arrangement is provided whereby the calling party may listen in on a line without being able to transmit speech currents thereover. An additional signal is provided at each call station for indicating to a calling party that the line connected to the call station is idle.

The novel features believed to be characteristic of the invention are set forth with particularity in the appended claims. The invention, both as to its organization and method of operation, together with further objects and advantages thereof, will best be understood by reference to the specification taken in connection with the accompanying drawings in which Figure 1 illustrates the application of the system to a congested trac area, wherein the streets are arranged to form the well-known grid type of pattern, and Fig. 2 illustrates the circuit arrangement of a portion of the system shown in Fig. 1.

Referring now Nmore particularly to Fig. 1 of the drawings, the street pattern there illustrated in typical of the thoroughfare arrangement provided to serve the main business district of a large city. The thoroughfares include a oneway First Street for the use of traffic proceeding in a westward direction, a one-way Second Street for the use of traiiic proceeding in an eastward direction, two-way Main and Broadway Streets for accommodating trailc proceeding in both the eastward and westward directions, and A, B and C Avenues intersecting at right angles the various enumerated streets. As illustrated in the drawings, these streets are arranged to serve twenty-four business blocks. The taxicab trac along the various streets of this business area is limited to cabs proceeding from either of the two cab stands lll and I I to speciiied destinations along one of the streets, for the purpose of picking up passengers, to cabs proceeding from loading points to passenger designated unloading points, and to cabs proceeding from distant loading points to passenger designated unloading points in the area. The summoning of cabs from the two cab stands l!) and Il to pickup points at which passengers are located is accomplished through the provision of two signaling networks individual to the two cab stands. To this end, each street is provided with call stations Sl, S2, C3, S4. S5, etc., located at convenient points along the two sides thereof. These call stations, which may be located in store and hotel entrances, for example, at spaced intervals along the streets. are connected to signaling lines or circuits which extendto control stations provided at the cab stands I and Il, respectively. Preferably, the call stations are so located that a person desiring a cab does not have to cross a street or walk more than one half of a block to reach a call station. More specifically, the call stations most conveniently located for trafc stops by vehicles proceeding in a westward direction are connected to signaling circuits which terminate at the control station provided at the cab stand I0, whereas the call stations most conveniently located for trafc stops by vehicles proceeding in an eastward direction are connected to signaling circuits terminating at the control station provided at the cab stand l l. Thus, the call stations SI to SIU, inclusive, are connected to the lines l, 2 and 3, all of which terminate at the control station located at the cab stand I0, while the call stations S20 to S25, inclusive, are all connected to the line 1 which extends to the control station provided at the cab stand Il. In this regard it will be noted that the cab stands I0 and Il are respectively located at the north- -east and southwest corners of the congested traffic area, so that a cab dispatched from the cab stand l0 may enter any one of the eastwest streets at the point therealong where trafnc congestion begins by making a right turn.

With the system arrangement described above, it will be noted that if a call is initiated at the call station S6, for example, at a time when the lines l to 5, inclusive, are idle, a signaling connection is set up between this station and the control station provided at the cab stand l0, whereby the dispatcher at this cab stand is informed that a passenger located at the station S6 desires transportation. A cab dispatched from this stand to pick up the waiting passenger may enter Main Street at the east side of the congested area by making a right turn, and is on the proper side of the street for picking up the passengers located at the calling station S6. Similarly, if a fare located at the station S23 signals the dispatcher at the cab stand H that a cab is desired, the dispatched cab may enter Main Street at the west side of the congested area by making one right turn, and is on the proper side of the street for making a stop at the calling station S23. On the other hand, if the fare is located at the station S26 disposed on the west side of B Avenue between Main and Broadway Streets, the cab dispatched from the cab stand Il may proceed to the loading point by making two right-hand turns, and is on the proper side of the street for the calling station. The call stations located along opposite sides of each one-way street are necessarily served by signaling circuits extending to the control station at the same cab stand. Thus, the call stations provided along First Street are most conveniently served by the cab stand I0 and, accordingly, these stations are all connected to lines terminating at the control station provided at this stand. Similarly, the call stations provided along Second Street are most conveniently served by cabs dispatched from the cab stand Il and, accordingly, all of these call stations are connected to signaling circuits terminating at the control station provided at the cab stand Il. The call stations along the intersecting avenues are, for the most part, connected to signaling circuits which extend to the control station provided at the cab stand from which cabs may be dispatched to the call stations by making a minimum number of right turns, thus eliminating traflic confusion. In this regard it will be noted that for a cab to proceed from the cab stand l0 to the call station S26 by making only right turns, four such turns would be required, whereas a, cab proceeding to this station from the cab stand Il can reach its destination by making only two right turns.

The individual signaling circuits or lines, as terminated at the control stations respectively provided at the two cab stands, serve partially to indicate to the dispatcher the location of call stations at which calls are initiated. This is accomplished by the particular circuit arrangemaking a stop at ment of the equipment illustrated in Fig. 2 of the drawings. As there illustrated, the equipment provided at the master station IOA located at the cab stand I comprises a line finder III at which are terminated all of the signaling circuits or lines extending to the call stations individually served by the cab stand I0. This line nder is of the well-known rotary type, comprising four sets of contacts, each including twenty-five contact points, Wipers II2 to II5, inclusive, individually associated with the contact sets, and a motor magnet IIS for driving the enumerated wipers over the contacts of their associated contact sets. The wiper carrying shaft of the switch I'II is also equipped with a pointer II1 arranged to cooperate with an indice bearing index plate II8 to identify the line or signaling circuit selected through each operation of the under.

The signaling equipment provided at the master station IIIA includes a telephone instrument, preferably ofthe well-known handset type, having embodied therein a transmitter I2I and a receiver |22 arranged to be supported upon a cradle which is provided with a plunger operated cradle switch including the contacts |25 and |25. More speoiiically, the cradle switch is so arranged that, with the handset supported by the cradle, the contacts |25 and |20 are respectively disengaged, and when the handset is removed from the cradle, these contacts are respectively operated into engagement. The transmitter I2I and receiver |22 are interconnected with the windings of an induction coil |23, a condenser |20 and the line wipers II3 and II5 of the nder switch III. For the purpose of supplying energizing current to the transmitter I2I and the various control relays and signals illustrated in the drawings, there is provided a source of direct current, not shown, but having its positive terminal connected to the various ground points illustrated in the drawings, and its negative terminal connected to a negative bus at which the various negative circuit terminals are commonly terminated. Current from this source is delivered to the transmitter I2I over paths including the voice currentv choke coils |21 and |28, a low impedance condenser I29 being provided to pass voice current through the lower winding of the induction coil |23 in preference to the choke coils |21 and |28 and the current source. The line equipment provided at the master station includes signal control relays Ili0, |50, etc., which are individually associated with the lines I, 25, etc., terminating in the bank contacts of the finder switch II I.

The common relay equipment comprises a iinder stop relay |50 and a pair of additional relays |10 and |80, which function to control the release of calling signaling circuits, the operation of a call meter I3I and the operation of an audible signal device |30. The signal equipment provided at the master station ISA also includes signal lamps |45, |55, etc., individual to the lines I, 25, etc., and a common call signal lamp |52.

The equipment provided at the call stations connected to each line may take either of two forms, depending upon Whether voice communication between the call stations and the master station is required. Thus, the equipment provided at the call stations SI and S2 served by the line I includes provisions for voice communication over this line', whereas the facilities provided at the call station S99 only include provisions for transmitting a calling signal over the'line 25 to the master station IBA. More specifically, the equipment provided at the call station SI cornyline I is idle.

through the make contacts prises a transmitter 205 and a receiver 205 arranged to be serially bridged across the conductors of the line I through operation of a call relay 200. Preferably, the bridging contacts 20| of fthe relay 200 are shuntedby a condenser 208, as indicated in dash lines, whereby a partyusing the station SI may listen in on the line I without' being able to transmit signal currents thereover. The energization of the call relay 200 is under the control of Aa call switch 204 which is of the non-locking push button type. Preferably, the call relay 200 is equipped with a target 201 arranged to be pivoted into a position behind the window 209 of the control panel provided at the station SI in response to energization of the relay 200, thereby to produce a signal that the The call relays provided at the other call stations are similarly equipped. The call station S2 is similar in arrangement to the station SI in that it includes a call relay 2I0, a call switch 2M, a transmitter 2 I5 and a receiver 2I5. The equipment provided at the call station S99, on the other hand, is somewhat more simple in character, since voice communicating facilities are not provided at this station. Thus, the call station S99 includes only a call relay 220 and `a call switch 224|. In connection with the lines arranged to provide signaling facilities only, it is desirable to equip these lines with additional line identification signaling apparatus in order to enable the controlstation attendant to distinguish between the two types of lines. To this end there is provided in association with the line a distinctive signal current source, the voltage of which is impressed upon the line 25 through a transformer |55 and a condenser I 51. This voltage may be interrupted in accordance with a predetermined the line 25 by means of any well-known type of code interrupter, and mayA be either continuously'applied to the line 25 over a path including the strap |58 or may be applied to the line 25 only when a call exists on this line by extending the voltage application path |52 of the signal control relay |50.

In the operation of the signaling network illustrated in Fig. 2 of the drawings, if a party desires to summon a cab to the call station SI, the push button call switch 204 is momentarily operated to complete a circuit for energizing the call relay 200 in series with the signal control relay M0 individual to the line I. This circuit extends from ground by way of the lower winding of the relay |40, the line rconductor Ib, the two windings of the relay 200 in series, the contacts of the switch 201|, the line conductor Ia and the upper winding of the relay I to the negative terminal of the current source. When thus energized, the relay 200 operates to bridge its low resistance upper winding across the conductors of the line I over a path including the contacts 202 and 203. Thus, a holding circuit is established for the relay 260 from which the high resistance lower winding of this relay is excluded and., as a result, the voltage drop between the conductors ,la and Ib of the line I is reduced by an amount such that the call relay 2I0, for example, will not operate if the call switch 2Itl is operated prior to the release of the call relay 200. Thus, all of the call stations served by the line I are prevented from gaining access to this line until the call relay 200 provided at the calling station Sl is released. In operating, the relay 200' also completes, at its contacts 20|, a path for bridging the code arbitrarily assigned tol series connected transmitter 205 and receiver 206 across the conductors of the line I. In addition, the relay 200 operates to rotate the target 201 in a clockwise direction, thereby to position this target behind the windowA 209 of the control panel in order to indicate to the party initiating the call that the line I is idle and the call has been transmitted to the master station.

The signal control relay |40 operates when energized in series with the windings of the call relay 200. At its contacts I4I, the relay |40 completes or prepares a circuit for energizing the signal lamp |45 individual to the line I, this circuit being completed only in the event the Wipers of the finder switch I I are standing in engagement with the contacts terminating the conductors of the line I. More speciiically, this circuit extends from ground by way of the wiper I I 4 and its associated lrst contact, the contacts I4| and the filament of the lamp |45 to the negative terminal of the current source. At its contacts |42, the relay |40 prepares or completes a circuit for energizing the stop relay |60, this circuit eX- tending from ground by way of the contacts |42, the wiper II2 and its associated rst contact, and the winding of the relay |60 to the negative terminal of the current source, and only being completed in the event the wipers of the iinder switch III engage their respective' associated rst contacts. Assuming that the wipers of the line nder III occupy this position, the relay |60 operates to open its contacts |6I and thus prevent operation of the motor magnet Iig. If, on the other hand, the wipers of the iinder switch III do not engage their respective associated iirst contacts at the 'time the call is initiated at the station SI, the relay |40, upon operating, completes, at its contacts |43, a circuit including the contacts ISI for energizing the motor magnet in parallel with the lamentof the common call signal lamp |32. When thus energized, the magnet IIS operates to complete, at its contacts |20, an obvious alternative operating circuit for the relay |00. The relay |60 now operates to open, at its contacts I6I, the path normally short-circuiting the resistor |62, and thus reduce the energization of the magnet |I9 sufficiently to cause the release thereof. When released in this manner, the spring biased pawl and ratchet mechanism of the finder switch I operates to advance the wipers ||2 to II5, inclusive, one step. The magnet IIS, in restoring, also opens its contacts |20 to interrupt the operating circuit for the relay |60, causing this relay to restore and recomplete the operating circuit for the magnet H9. The interrelated operation of the magnet I9 and the relay |60 continues until the wipers of the nder switch III are positioned in engagement with their respective associated first contacts, at which time the relay |60 is energized over the above-traced circuit extending to ground through the make contacts |42. When this circuit is completed, the relay I 60 remains in its operated position to prevent further operation of the magnet II9, with the result that further stepping of the Wipers II2 to |I5, inclusive, is prevented. In addition, the enumerated wipers, upon engaging their associated first contacts, connect the conductors of the line I to the substation equipment provided at the master station IOA, and complete the above-traced circuit for energizing the line identication lamp |45. Further, the pointer ||1 is positioned opposite the index designating `the line I to give an indication to the dispatcher that the line I is calling. From a consideration of the signaling arrangement, it will be observed that the lamp |32, When energized, indicates that one of the lines of the system has a call thereon, but does not indicate which line is calling. The lamp I 45, on the other hand, when illuminated indicates that the line I is calling, and this signal is supplemented by the indication given by the pointer ||1 cooperating with the index plate 8. A further audible signal is produced through operation of the buzzer I 30, this buzzer being energized over a circuit including the contacts |43 and |14 in response to operation of the relay |40.

The dispatcher, upon receiving these signals, may remove the handset from its supporting cradle for the purpose of answering the call. In response to this operation, the cradle switch is operated to move the switch springs |25 and I 26, respectively, into engagement. At the springs |25, a circuit including the choke coils |21 and |28 is completed for delivering energizing current to the transmitter |2| At the springs |26, an obvious circuit is completed for energizing the relay |10. The relay |10, upon operating, closes its contacts |12, to complete an obvious circuit for energizing the slow-to-release relay |80. At its contacts I1|, the relay |10 opens a point in the low resistance bridging path which is subsequently established across the conductors of the line in order to cause the release of the operated call relay 200. At its contacts |13, the relay |10 completes an obvious circuit for energizing the call meter I3I, whereby the call is registered. At its contacts |14, the relay |10 interrupts the operating circuit for the buzzer |30, thus terminating the audible signal indication. The relay operates shortly following the operation of the relay |10, and closes its contacts I8I to prepare the low resistance bridge across the conductors of the line I. At its contacts |82, the relay |80 opens the operating circuit for the call meter |3I. Following the operations just described, a two-way communication connection is established between the master station IOA and the call station SI, this connection including the two sides of the line I. In this regard it will be noted that current for energizing the transmitter 205 provided at the call station SI is supplied to this transmitter over the line conductors I a and Ib through the windings of the signal control relay |40. With this communication connection established, the calling party may inform the dispatcher as to the number of the call station, thus identifying its location so that a cab may be dispatched thereto.l

After the call is disposed of in this manner, the equipment may be released under the control of the dispatcher. More specifically, when the handset provided at the master station IOA is replaced upon its supporting cradle, the cradle switch is operated to cause the disengagement of the contacts |25 and |26, respectively. As a consequence, the current supply circuit to the transmitter |2| is broken and the relays |10 and |80 are caused sequentially to restore. During the period which elapses between the release of the relay |10 and the release of the relay |80, the low resistance bridge referred to above is completed between the conductors Ia and |b of the line I, this bridge including the operated make contacts |8I and the restored break contacts I1I With this path completed, the low resistance holding winding of the operated call relay 200 is eiectively short-circuited, causing this call relay to restore. When the relay |80 restores, shortly following the release of the call relay 200, the bridging path across the conductors oi the line is interrupted to cause the deenergization and release of the signal control relay |40. The relay |40, upon restoring, opens its contacts |4| and |43 to deenergize the signal lamps |45 and |32. At its contacts |43, the relay |40 also opens a point in the operating circuits for the buzzer |30 and the motor magnet H9. At its contacts |42, the relay |40 interrupts the abovetraced. circuit for energizing the stop relay |60. Following the release of the relay |00, the equipment is fully restored to normal in readiness to handle another call.

As indicated above, the arrangement of the signaling network is such that each line may handle only one call at a time. Thus, if the call relay 2|0, provided at the station S12, is operated at the time the above-described call is initiated at the station SI, the voltage difference Ibetween the conductors la and lb of the line is insufflcient to cause the operation of the call relay 200 provided at the calling station Sl. The calling party, by observing that the target 201 is not moved to a position behind the window 209, is informed that the line is in use. Assuming that the condenser 203 is employed in the circuit provided at the call station Sl, the calling party may, by listening in on the line determine when the line is released by the dispatcher at the master station |A and thus ascertain without undue delay when to again initiate the call. It will be observed that with the transmitter 205 and the receiver 206 only reactively coupled to the line l, energizing current is not supplied to the transmitter 205, and, accordingly, the party using the call station Sl cannot break in upon the conversation being held between the call station S2 and the master station |0'A.

The arrangement of the system is such that the initiation of a call on one of the signaling lines does not preclude the later initiation of a call on another of the lines before the first call is released, although the later initiated call will be extended to the master stationby the line nder only after the rst call is disposed of. Thus, if the master station equipment is occupied with a call originating on the line for example, such that the relays |40, |60, and |80 are operated and a call is initiated at the call station S59, for example, through operation of the switch 224, the call relay 220 is energized and locks up in series with the signal control relay |50. Due to the energized condition of the relay |00, however, the nder switch Il| is prevented from operating to seize the calling line 25. 'Ihe tworelays 220 and |50 remain operated during the release of the master station control equipment and the operated relays associated with the line Immediately the relay |60 restores to terminate this release operation, the circuit for energizing the motor magnet |9 is recompleted, whereby operation of the nder switch is initiated to seize the line 25 upon which the call is waiting. The manner in which the second call, namely, that present on the line 25, is extended to the master station |0A, and the equipment is released under the control of thedispatcher attending this station, is exactly the same as described above and will readily be apparent from the foregoing explanation. In this case, however, it will be noted ythat when the wipers of the nder switch III are positioned to engage the contacts terminating the conductors of the line 25, the characteristic signal volt.- age identifying the line 25 is transmitted to the receiver |22 to indicate to the dispatcher that the line 25 is calling, thus supplementing the visual signals given by the lamp |55 and the indicating mechanism of the iinder switch. More specifically, the path traversed by this signal current extends from the ungrounded terminal of the secondary winding ofthe transformer |56 by way of the condenser |57, the contacts |52, the wiper ||5 and its associated twenty-fth contact, the receiver |22, the upper winding: of the induction coil |23, the condenser |24, the wiper l|3 and its associated twenty-fth contact, and through the lowerfwinding of the relay |50 to ground. The coded signals produced by the receiver |22 in response to the signal current traversing this path positively identifies the calling line to the dispatcher. If desired, the make contacts |52 included in this path may be omit.- ted, the upper terminal of the condenser |53 being connected directly to the upper conductor of the line 25 by means of a strap |58.

From the above explanation, it will be apparent that successively initiated calls on the various signaling lines are handled in a predetermined order in accordance with the termination of these lines in the bank contacts of the line iinder and that, as each communication or signalling connection is released, the next line in order having a call present thereon is connected with the master station. By virtue of this arrangement, the call stations associated with any one line are prevented from monopolizingl the call answer facilities of the master station |0A to the exclusion of other lines.

While there has been described what is at present considered to be the preferred embodiment of the invention, it will be understood that various modifications may be made therein, and it is contemplated to cover in the appended claims all such modications as fall within the true spirit and scope of the invention.

What is claimed is:

1. In a telephone system, a line, a plurality of call stations associated with said line, each of said stations including a transmitter and a re,- ceiver and a call relay operative to lconnect the associated transmitter and receiver to said line, means provided at one of said call stations for rendering the receiver at said one station operative to reproduce signall currents transmitted over said line when the associated control relay is released, and a master station including signal control means operative in response to operation of any one of said relays.

2. In a telephone system, a line, a plurality of call stations associated with said line, each of said stations including a transmitter and a receiver and a call relay operative to connect the associated transmitter and receiver to said line, the receiver provided at at least one of said call stations being reactively coupled to said line to respond to signal currents transmitted thereover regardless of the position of the associated call relay, and a master station including signal control means operative in response to operation of any one of said relays.

. 3. In a signaling system, a line, a plurality of call stations associated with said line, a master station including a signal control relay, each of said stations including a call relay, means at each call station for connecting the associated call relay in series with said control relay, and

means at said master station for establishing a low resistance shunt across any operated call relay in order to cause the release thereof.

4. In a signaling system, a line, a plurality of call stations associated with said line, a master station including a signal control relay, each of said stations including a call relay, means at each call station for connecting the associated call relay in series with said control relay, a receiver at said master station connected to respond to signals transmitted over said line from said call stations, a support for said receiver, and means operative in response to replacement of said receiver upon said support for establishing a low resistance shunt across any operated call relay in order to cause the release thereof.

5. In a signaling system, a line, a plurality of call stations associated with said line, a master station including a signal control relay, each of said call stations including a call relay operative to complete an operating circuit for said signal control relay, and means at said master station for establishing a low resistance shunt across any operated call relay in order to cause the release thereof.

6. In a signaling system, a line, a plurality of call stations associated with said line, a master station including signal control means, each of said call stations including a call relay operative to cause the operation of said signal control means, and means at said master station for establishing a low resistance shunt across any operated call relay in order to cause the release thereof.

7. In a signaling system, a line, a plurality of call stations associated with said line, a master station including signal control means, each of said call stations including a call relay operative to cause the operation of said signal control means, electric circuit means interconnecting said relays to prevent the concurrent operation of more than one of said relays, and means at said master station for establishing a low resistance shunt across any operated call relay in order to cause the release thereof.

8. In asignaling system, a line, a plurality of call stations associated with said line, a master station including signal control means, a receiver at said master station connected to rel spond to signals transmitted over said line, a support for said receiver, each of said call stations including a call relay operative to cause the operation of said signal control means, and means operative in response to replacement of said receiver upon said support for establishing a 1ow= resistance shunt across any operated call relay in order to cause the release thereof.

9. In a signaling system, a line, a plurality of call stations associated with said line, a master station including signal control means, a receiver at said master station connected to respond to signals transmitted over said line, a support for said receiver, each of said call stations including a call relay operative to cause the operation of said signal control means, and means operative in response to replacement of said receiver upon said support for causing the release of any operated call relay.

10. In a signaling system, a line, a plurality of call stations associated with said line, a master station including signal control means, a receiver at said master station connected to respond to signals transmitted over said line, a support for said receiver, each of said call stations including a call relay operative tocause the operation of said signal controlmeans, electric circuit means interconnecting said relays to prevent the concurrent operation of more vthan one of said relays, and means operative in response to replacement of said receiver upon said support for causing the release of any operated call relay.

'11. In a signaling system, a line, a plurality of call stations associated with said line, a source of current, a master station including a' signal control relay having windings bridged across the conductor of said line in series with said current source, each of said call stations including a call relay and a switch for bridging the windings of the associated call relay across the conductors of said line for energization in series with the windings of said control relay, and means responsive to the operation of one of said call relays for establishing a low resistance shunt across the windings of the other call relays in order to prevent the operation thereof.

l2. In a signaling system, a line, a plurality of call stations associated with said line, a source of current, a master station including a signal control relay having windings bridged across the conductors of said line in series with said current source, each of said call stations including a call relay and a switch for bridging the windings of the associated call relay across the conductors of said line for energization in series with the windings of said control relay, and means at said master station for establishing a low resistance bridge across the conductors of said line in order to cause the release of any operated one of said call relays. Y

13. In a signaling system, a line, a plurality of call stations, associated with said line, a source of current, a master station including a signal control relay having windings bridged across the conductors of said line in series with said current source, each of said call stations including a call relay and a switch for bridging the windings of the associated call relay across the conductors of said line for energization in series with the windings of said control relay, means at said master station for establishing a low resistance bridge across the conductors of said line in order to cause the release of any operated one of said call relays, and means responsive to the operation of one of said call relays for establishing a low resistance shunt across the windings of the other call relays in order to prevent the operation thereof.

14. In a signaling system, a line, a plurality of call stations associated with said line, a source of current, a master station including a signal control relay having windings bridged across the conductors of said line in series with said current source, each 4of said call stations including a call relay having a high resistance operating Winding and a low resistance holding'winding, a switch at each of said call stations for connecting the windings of the associated linev relay across the conductors of said lineto cause the energization of the associated call relay in series with said signal -contro-l relay, and means, responsive to the operation of'any one of saidcall relays for short-circuiting the operating winding of the operated callrelay, thereby to establish a low resistance bridge across the conductors of said line which prevents operation of the other call relays.

15. In a signaling system, a line, a plurality of call stations associated YwithV said line, asource of current, a master station including a signal control relay having windings bridged across the conductors of said line in series with said current source, each of said call stations including a call relay having a high resistance operating winding and a low resistance holding Winding, a switch at each of said call stations for connecting the windings'of the associated call relay across the conductors of said line to cause the energizatlon of the associated call relay in series with said signal control relay, means responsive to the operation of any one of said call relays for short-circuiting the operating winding of the operated call relay, thereby to establish a low resistance bridge across the conductors of said line which prevents operation of the other call relays, means also responsive to the operation of said one call relay for bridging the holding winding of said one call relay across the lconductors of said line independently of its associated switch, and means at said station for short-circuiting the holding winding of said one call relay over a path including the conductors of said line, there.- by to cause the release of said one call relay.

16. In a signaling system, a line, a plurality of call stations associated with said line, a'master station including signal control means, each of said call stations including a call relay operative to cause the operation of said signal control means, means for preventing the operation of more than one of said relays, and a signal device at each of said call stations controlled by the associated call relay.

17. In a signaling system, a line, a plurality of call stations associated with said line, a master station including signal control means, each of said call stations including a call relay. operative to cause the operation of said signal control means, means for preventing the operation of more Athan one of said relays at a time, and means comprising signal devices individually controlled by said relays for indicating to call station users the idle or busy condition of said line.

18. In a signaling system, a line, a plurality of call stations associated with said line, a master station including signal control means, a receiver at said master station connected to respond to signals transmitted over said line, a support for said receiver, each of said call stations including a call relay operative to cause the operation of said signal control means, a call meter, and means operative in response to removal of said receiver from said support for causing the operation of said meter and in response to replacement of said receiver upon said support to cause the release of any operated call relay.

19. In a signaling system, a line, a plurality of call stations associated with said line, a master station including signal control means, a receiver at said master station connected to respond to signals transmitted over said line, a support for said receiver, each of said call stations including a call relay operative to vcause the operation of said signal control means, a call meter, a pair of relays sequentially operative in a predetermined order in response to removal of said receiver from said support and sequentially released in the same order in response to replacement of said receiver upon said support, means responsive to the operation of said pair of relays for causing the operation of said meter, and means operative in response to the release of said pair of relays for establishing a low resistance shunt across an)T operated call relay in order to cause the release thereof.

20. A public service system for a plurality of streets including at least one two-Way street, said system comprising call signals spaced along said two-Way street upon opposite sides thereof, a pair of control stations respectively located on opposite sides of said two-way street, a signal circuit connecting the call stations located along one side of said two-Way street with one of said control stations, and another signaling circuit connecting the call stations located along the opposite side of said two-Way street with the other of said control stations.

21. A cab call system for a plurality of streets including at least one two-way street and a oneway street extending substantially parallel with said two-way street, said system comprising call signals spaced along said one and two-way streets upon opposite sides thereof, cab stands respectively located on opposite sides of said two- Way street, control stations at said cab stands, a signaling circuit connecting the call stations 1ocated along one side of said two-way street with the control station at one of said cab stands, a second signaling circuit connecting the call stations located along the opposite side of said twoway street with the control station at the other of said cab stands, and a third signaling circuit connecting the call stations located along at least one side of said one-way street with the control station at a predetermined one of said cab stands.

BERNARD D. WILLIS. 

